Thiol and sulfur-containing O-(meth)acrylate compounds and use thereof

ABSTRACT

A sulfur-containing O-(meth)acrylate compound of the following formula (1) is useful as a starting material for a resin composition used in optical applications such as a lens;                    
     wherein R represents hydrogen atom or methyl group; 1 represents an integer from 1 to 3; B is                    
     when B is                    
      n is 2; m is 1 or 2; A is selected from the following groups:                    
     wherein m represents 1 or 2; each ring may be substituted by one or more alkyl, alkylthio or alkoxy groups having 1 or 2 carbon atoms; p and q are 0 or 1, while m is 1 when p is 1; 
     when B is                    
      n is 1; m is 2 or 3; A is selected from the following groups: 
     
       
         —(CH 2 ) r —S—(CH 2 ) r —, —(CH 2 ) r —S—S—(CH 2 ) r —. 
       
     
      —(CH 2 ) r —S—(CH 2 ) s —S—(CH 2 ) r —and 
     and 
     
       
         
         
             
             
         
       
     
     wherein r and s are an integer from  1  to  3;    
     when B is                    
      n is  1;  m is  2;  A is selected from the following groups: 
     
       
         —(CH 2 ) r —S—(CH 2 ) r —, —CH 2 ) r —S—S—(CH 2 ) r   
       
     
     and 
     
       
         —(CH 2 ) r —S—(CH 2 ) s —S—(CH 2 ) r — 
       
     
     wherein r and s are an integer from  1  to  3.

This application is a divisional of application Ser. No. 09/590,015,filed on Jun. 9, 2000, which is a divisional of application Ser. No.09/157,985, filed on Sep. 22, 1998, now U.S. Pat. No. 6,114,485, whichin turn is a divisional of application Ser. No. 08/861,024, filed on May21, 1997, now U.S. Pat. No. 5,916,987.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a novel sulfur-containing O-(meth)acrylatecompound; a process for preparation of the sulfur-containingO-(meth)acrylate compound, comprising dithioacetalization,thio-esterification or thio-urethanization of a novel thiol compoundfollowed by dehydrohalogenation; an optical resin composition comprisingthe sulfur-containing O-(meth)acrylate compound; and an optical resinprepared by polymerization of the composition.

2. Description of the Related Arts

A plastic lens is lighter and less brittle than an inorganic lens, anddyeable, which has been therefore rapidly gaining prevalence in theareas of optical devices such as lenses for eyeglasses and cameras.Currently, the resins which may be widely used for these applications,include those prepared by radical polymerization of diethylene glycolbis(allylcarbonate) (referred to as ‘D.A.C.’). These resins have variousfeatures such as excellent impact resistance, lightness, excellenttintability, and good processability including machinability andabradability. These resins, however, have a low refractive index (n_(d))of about 1.50 so that it is necessary to increase the center thicknessand the edge thickness, and when such requirements are met, the lens isunavoidably thickened on the whole. Therefore, a lens having a higherrefractive index has been desired.

Resins with a higher refractive index than D.A.C. resin are known; forexample, polythiourethane resins (e.g., JP-A 63-46213);sulfur-containing O-(meth)acrylate resins. (e.g., JP-A 1-128966,3-217412 and 4-161410); and thio(meth)acrylate resins (e.g., JP-A63-188660 and JP-B 3-59060), in which sulfur atoms are introduced. Apolythiourethane resin is well-balanced in its properties, that is, hasa high refractive index and good impact resistance and the like. Whenrapidly polymerizing it, the resin, however, tends to be inhomogeneouslypolymerized, and thus the polymerization inevitably takes longer time toobtain an optically homogeneous lens. Furthermore, during processing itby cutting and abrasion, sulfur odor may generate.

A sulfur-containing O-(meth)acrylate resin or a thio(meth)acrylate resincan be prepared by rapid polymerization by means of UV rays or the like.In general, a resin produced may, however, have inadequate strength orimpact resistance, that is, it may be brittle and breakable. Recently, aresin for a lens has been required to have processing strength suitablefor a two-point processing widely used in the area of a lens foreyeglasses, and a center of a lens for eyeglasses has been beingthinner. Thus, there has been a demand for a resin having higherstrength and impact resistance. Furthermore, since a thio(meth)acrylatecompound is less stable, it may gel or tend to be uncontrollably rapidlypolymerized and require complex operations. Therefore, there has been aneed for further improvement to solve these problems.

SUMMARY OF THE INVENTION

An objective of this invention is to provide an optical resincomposition which has a good handling properties and can be rapidlypolymerized, and which gives an optical resin having excellent opticalproperties, particularly a high refractive index and excellent impactresistance, as well as generating less unpleasant odor duringprocessing.

We have intensively attempted to achieve the above object and have foundthat some kind of sulfur-containing O-(meth)acrylate compounds areeffective, and have completed this invention. That is to say, thisinvention relates to a sulfur-containing O-(meth)acrylate compound ofthe following formula (1):

wherein R represents a hydrogen atom or methyl group; represents aninteger from 1 to 3; B is

when B is

 then n is 2; m is 1 or 2; A is selected from the following groups:

wherein m represents 1 or 2; each ring may be substituted by one or morealkyl, alkylthio or alkoxy groups having 1 or 2 carbon atoms; p and qare 0 or 1, while m is 1 when p is 1;

when B is

 then n is 1; m is 2 or 3; A is selected from the following groups:

—(CH₂)_(r)—S—(CH₂)_(r)—, —(CH₂)_(r)—S—S—(CH₂)_(r)—,

—(CH₂)_(r)—S—(CH₂)_(s)—S—(CH₂)_(r)—

and

wherein r and s are an integer from 1 to 3;

when B is

 n is 1; m is 2; A is selected from the following groups;

—(CH₂)_(r)—S—(CH₂)_(r)—, —(CH₂)—S—S—(CH₂)_(r)—

and

—(CH₂)_(r)—S—(CH₂)_(s)—S—(CH₂)_(r)—

wherein r and s are an integer from 1 to 3

This invention also relates to a process for preparation of thesulfur-containing O-(meth)acrylate compound of the above formula (1),comprising dithioacetalizing a thiol compound represented by thefollowing formula (2):

wherein X represents Cl or Br; R represents hydrogen atom or methylgroup; and l represents an integer from 1 to 3, with a compound havingat least one aldehyde group in its molecule; thioesterificating thethiol compound with a compound having at least two carboxyl groups inits molecule or thiourethanizing the thiol compound with a compoundhaving at least two isocyanate groups in its molecule; and thendehydrohalogenating the product.

The compound of the above formula (2) is also novel, which, as anintermediate of the sulfur-containing O-(meth)acrylate of the aboveformula (1), is covered by this invention.

Further, this invention also relates to an optical resin compositioncomprising the sulfur-containing O-(meth)acrylate compound of the aboveformula (1), and a sulfur-containing resin and lens formed bypolymerizing the composition.

The sulfur-containing O-(meth)acrylate compound of this invention isnovel, has improved stability as a monomer and has excellentworkability. The optical resin composition of this invention can berapidly polymerized, giving an optical resin which has excellent opticalproperties, in particular a high refractive index and excellent impactresistance, as well as generates less unpleasant odor during processing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 10 are ¹H-NMR charts for the respective compounds obtained inExamples 1 to 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention will be detailed below.

The sulfur-containing O-(meth)acrylate compound of this inventionrepresented by formula (1) can be prepared from the thiol compoundrepresented by formula (2). Specifically, the compound of formula (1)can be prepared by ditihoacetalization, thioesterification orthiourethanization of the thiol compound with a compound having afunctional group capable of reacting with the mercapto group of thethiol compound, such as aldehydes, carboxylic acids and isocyanates, andthen dehydrohalogenation of the product.

The thiol compound of this invention represented by formula (2) can beprepared as follows. 2-Mercaptoethanol, 3-mercaptopropanol or the likeis heated at 10 to 200° C. with a compound such as 3-chloropropionicacid, 3-bromopropionic acid, 3-chloro-2-methylpropionic acid and3-bromo-2-methylpropionic acid, in the presence of a catalyst such asp-toluenesulfonic acid, sulfuric acid and hydrochloric acid, in asolvent, while removing water generated, that is, via adehydro-esterification. Alternatively, in the light of stability of thestarting material such as 2-mercaptoethanol or 3-mercaptopropanol, thedehydro-esterification may be conducted with mild heating of thereaction system under a reduced pressure of 20 to 400 mmHg to give thethiol.

Using the thiol compound of this invention, it is possible to introducea sulfur atom into a product molecule to further improve its refractiveindex. Furthermore, the thiol compound of this invention can be derivedto an O-(meth)acrylate compound after reaction in its mercapto group andthen dehydrohalogenation, that is, it can easily react with a compoundhaving a functional group capable of reacting with a mercapto group suchas aldehydes, carboxylic acids and isocyanates to give a desiredsulfur-containing O-(meth)acrylate compound with a high purity.

When definition B is

the sulfur-containing O-(meth)acrylate compound of this inventionrepresented by formula (1) can be prepared with a compound having atleast one aldehyde group and the thiol compound of formula (2) by aprocess comprising the following two steps.

First, the compound having at least one aldehyde group is heated withthe above thiol compound at 10 to 200° C. in a solvent, in the presenceof a catalyst such as p-toluene-sulfonic acid, sulfuric acid andhydrochloric acid, while removing water generated, that is, viadehydtodithioacetalization. Next, the mixture was treated with a base at−20 to 60° C. to dehydrohalogenate the product to give the desired(meth)acrylated compound.

The bases used as a hydrogen-halide trap in the latter (meth)acrylationstep include, but not limited to, generally-used bases; for example,trialkanolamines such as trimethylamine and triethylamine, pyridine,sodium hydroxide and potassium hydroxide.

The compounds having at least one aldehyde group includereadily-available aldehyde compounds and those having any of thefollowing structures:

wherein m represents 1 or 2; each ring may be substituted by one or morealkyl, alkylthio or alkoxy groups having 1 or 2 carbon atoms; p and qare 0 or 1, while m is 1 when p is 1.

The specific aldehydes which can be used, include benzaldehyde,2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-ethylbenzaldehyde,2,4-dimethylbenzaldehyde, 2,5-dimethylbenzaldehyde,3,4-dimethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde,2,4,6-trimethylbenzaldehyde, 2-methoxybenzaldehyde,3-methoxybenzaldehyde, 4-methoxybenzaldehyde, 2,3-dimethoxybenzaldehyde,2,4-dimethoxybenzaldehyde, 2,5-dimethoxybenzaldehyde,3,4-dimethoxybenzaldehyde, 3,5-dimethoxybenzaldehyde,2-ethoxybenzaldehyde, 3-ethoxybenzaldehyde, 4-ethoxybenzaldehyde,phthalaldehyde, isophthalaldehyde, terephthalaldehyde,2-methylthiobenzaldehyde, 4-methylthiobenzaldehyde,4-methylthiomethylbenzaldehyde, phenylacetoaldehyde,2-thiophenealdehyde, 3-thiophenealdehyde, 3-methyl-2-thiophenealdehyde,4-methyl-2-thiophenealdehyde, 5-methyl-2-thiophenealdehyde,5-ethyl-2-thiophenealdehyde, 5-methylthiothiophene-2-aldehyde,2,3-thiophenedialdehyde, 2,5-thiophenedialdehyde, 1-naphthoaldehyde,2-naphthoaldehyde, 1,2-naphthalenedialdehyde and2,3-naphthalenedialdehyde.

Each sulfur-containing O-(meth)acrylate of this invention represented byformula (1) has a main chain with the same structure and thus has anessentially equal distance between intramolecular crosslinking points.Therefore, it is possible to select resins with different opticalproperties by altering an aldehyde compound constituting a motherskeleton, without largely varying thermal properties, mechanicalproperties, or the like of a resin obtained.

Similarly, when definition B is

the sulfur-containing O-(meth)acrylate compound of this inventionrepresented by formula (1) can be prepared with a sulfur-containingcarboxylic acid compound having at least two carboxyl groups in itsmolecule and the thiol compound of formula (2) by a process comprisingtwo steps of thio-esterification and dehydrohalogenation.

When definition B is

the sulfur-containing O-(meth)acrylate compound of this inventionrepresented by formula (1) can be prepared with a compound having twoisocyanate groups in its molecule and the thiol compound of formula (2)by a process comprising two steps of thiourethanization anddehydrohalogenation.

When definition B is

the sulfur-containing carboxylic acid constituting a mother skeleton forthe sulfur-containing O-(meth)acrylate compound is a readily availablecarboxylic acid, having any of the following structures:

HOOC—(CH₂)_(r)—S—(CH₂)_(s)—S—(CH₂)_(r)—COOH,

HOOC—(CH₂)_(r)—S—(CH₂)_(r)—COOH,

HOOC—(CH₂)_(r)—S—(CH₂)_(r)—COOH

and

wherein r and s are an integer from 1 to 3.

The specific acids which can be used, include thiodiglycolic acid,thiodipropionic acid, 4,4-thiodibutanoic acid, dithiodiglycolic acid,dithio-dipropionic acid, 4,4-dithiodibutanoic acid,methylene-bis(thioglycolic acid), methylenebis(thiopropionic acid),methylenebis(thiobutanoic acid), ethylenebis(thioglycolic acid),ethylenebis(thiopropionic acid), ethylenebis-(thiobutanoic acid),methinetris(thioglycolic acid), methinetris(thiopropionic acid), andmethinetris-(thiobutanoic acid). These sulfur-containingO-(meth)acrylate compounds are more hydrophilic because of having anumber of intramolecular ester bonds, which is expected to give a lensimproved in tintability.

When definition B is

the isocyanate compound constituting a mother skeleton for thesulfur-containing O-(meth)acrylate compound has any of the followingstructures:

OCN—(CH₂)_(r)—S—(CH₂)_(r)—NCO,

OCN—(CH₂)_(r)—S—S—(CH₂)_(r)—NCO

and

OCN—(CH₂)_(r)—S—(CH₂)_(s)—S—(CH₂)_(r)—NCO

wherein r and s are an integer from 1 to 3.

The specific compounds which can be used, include diisocyanatomethylsulfide, diisocyanatoethyl sulfide, diisocyanatopropyl sulfide,diisocyanatomethyl disulfide, diisocyanatoethyl disulfide,diisocyanatopropyl disulfide, bis(isocyanatomethylthio)methane,bis(isocyanatoethyl-thio)methane and bis(isocyanatopropylthio)methane.Thus obtained sulfur-containing O-(meth)acrylate compounds are expectedto have improvement in a refractive index and resin strength such asimpact resistance because of having an intramolecular thiourethane bond.

In these reactions, if necessary, organic solvents can be used. Thesolvents which can be used, are, but not limited to, those which do notreact with starting materials used in the reactions. Such organicsolvents include aliphatic and aromatic hydrocarbones and halogenatedhydrocarbons such as benzene, toluene, xylenes, hexane, heptane,petroleumether, chloroform, methylene chlorides and ethylene chlorides;ethers such as diethylether, dioxane and tetrahydrofuran; ketones suchas acetone and methyl ethyl ketone; and N,N-dimethylformamide. Thesolvents used are selected based on materials used, type of the reactionor the like, as appropriate.

These thiol, aldehyde, sulfur-containing carboxylic acid and isocyanatecompounds may have been, if necessary, purified by distillation or thelike.

The sulfur-containing O-(meth)acrylate compounds prepared by theseprocesses are improved in stability as a monomer, are relatively hard togel and are more easily handled in comparison with thio(meth)acrylatecompounds.

The optical resin compositions of this invention include thosecomprising the sulfur-containing O-(meth)acrylate compound of thisinvention, and those comprising the sulfur-containing O-(meth)acrylatecompound of this invention and at least one of monomers co-polymerizablewith the acrylate of this invention, or polythiol compounds. For thecomposition comprising monomers other than the acrylate of thisinvention or polythiol compounds, the sulfur-containing O-(meth)acrylatecompound of this invention is contained in more than 20% by weight,preferably more than 40% by weight, more preferably more than 60% byweight, to the total amount of the sulfur-containing O-(meth)acrylatecompound and the other monomers or the polythiol compounds.

The monomers co-polymerizable with the acrylate of this invention or thepolythiol compounds may be selected, based on their purposes such as,but not limited to, adjustment of optical properties including arefractive index, various physical properties including impactresistance and specific gravity and parameters relevant to handlingincluding viscosity of the monomer. The co-polymerizable monomers or thepolythiol compounds may be used solely or in combination of two or morecomponents.

The co-polymerizable monomers include (meth)acrylate compounds such asbenzyl acrylate, benzyl methacrylate, butoxyethyl acrylate, butoxymethylmethacrylate, cyclohexyl acrylate, cyclohexyl methacrylate,2-hydroxyethyl acrylate, 2-hydroxymethyl methacrylate, glycidylacrylate, glycidyl methacrylate, phenoxyethyl acrylate, phenoxyethylmethacrylate, phenyl methacrylate, ethylene glycol diacrylate, ethyleneglycol dimethacrylate, diethylene glycol diacrylate, diethylene glycoldimethacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycoldimethacrylate, polyethylene glycol diacrylates, polyethylene glycoldimethacrylates, neopentyl glycol diacrylate, neopentyl glycoldimethacrylate, ethylene glycol bisglycidyl acrylate, ethylene glycolbisglycidyl methacrylate, bisphenol A diacrylate; bisphenol Adimethacrylate, 2,2-bis(4-acryloxyethoxyphenyl)propane,2,2-bis(4-methacryloxyethoxyphenyl)propane,2,2-bis(4-acryloxydiethoxyphenyl)propane,2,2-bis(4-methacryloxydiethoxyphenyl)propane, bisphenol F diacrylate,bisphenol F dimethacrylate, 1,1-bis(4-acryloxyethoxyphenyl)methane,1,1-bis(4-methacryloxyethoxyphenyl)methane,1,1-bis(4-acryloxydiethoxyphenyl)methane,1,1-bis(4-methacryloxydiethoxyphenyl)methane,1,1-bis(4-acryloxyethoxyphenyl)sulfone,1,1-bis(4-methacryloxy-ethoxyphenyl)sulfone,1,1-bis(4-acryloxydiethoxyphenyl)-sulfone,1,1-bis(4-methacryloxydiethoxyphenyl)sulfone, dimethyloltricyclodecanediacrylate, trimethylolpropane triacrylate, trimethylolpropanetrimethacrylate, glycerol diacrylate, glycerol dimethacrylate,pentaerythritol triacrylate, pentaerythritol tetraacrylate,pentaerythritol tetramethacrylate, methylthio acrylate, methylthiomethacrylate, phenylthio acrylate, benzylthio methacrylate,xylylenedithiol diacrylates, xylylenedithiol dimethacrylates,mercaptoethyl sulfide diacrylate and mercaptoethyl sulfidedimethacrylate; allyl compounds such as allyl glycidyl ether, diallylphthalate, diallyl terephthalate, diallyl isophthalate, diallylcarbonate and diethylene glycol bis(allylcarbonate); vinyl compoundssuch as styrene, chlorostyrenes, methylstyrenes, bromostyrenes,dibromostyrene, divinylbenzenes and 3,9-divinylspiro-bi(m-dioxane); anddiisopropenylbenzene.

The polythiol compounds include 1,2-ethanedithiol, 1,3-propanedithiol,1,2,3-propanetrithiol, 2,3-dimercapto-1-propanol, diethylene glycolbis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate),trimethylolpropane bis(2-mercaptoacetate), trimethylolpropanebis(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate),pentaerythritol tetrakis(3-mercaptopropionate), 1,2-diinercaptobenzene,1,3-dimercaptobenzene, 1,4-dimercaptobenzene,1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene,1,4-bis(mercaptomethyl)benzene, 1,2,3-trimercaptobenzene,1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene,1,2,3-tris(mercaptomethyl)benzene, 1,2,4-tris(mercaptomethyl)benzene,1,3,5-tris(mercaptomethyl)benzene, 4,4′-thiobisbenzenethiol,bis(2-mercaptoethyl) sulfide, bis(2-mercaptoethylthio)methane,1,2-bis(2-mercaptoethylthio) ethane,1,3-bis(2-mercaptoethylthio)propane,1,2,3-tris(2-mercaptoethylthio)propane,tetrakis(2-mercaptoethylthiomethyl)methane,1,2-bis(2-mercaptoethylthio)-3-mercaptopropane,4,8-bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol,2,5-dimercapto-1,4-dithiane, 2,5-dimercaptomethyl-1,4-dithiane and2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane. The co-polymerizablemonomer is preferably the compound represented by the following formula(3):

wherein R represents a hydrogen atom or methyl group; t and u representan integer from 0 to 4; and E represents —CH₂—, —C(CH₃)₂—, —S— or —SO₂—.

The optical resin of this invention is prepared by polymerizing theoptical resin composition of this invention; specifically, bypolymerizing solely the sulfur-containing O-(meth)acrylate compound ofthis invention or co-polymerizing the sulfur-containing O-(meth)acrylatecompound of this invention and another co-polymerizable monomer or thepolythiol compound.

A polymerization procedure for providing the optical resin of thisinvention may be, but not limited to, any of the known radicalpolymerization methods.

The polymerization may be initiated by using a radical initiator such asa variety of peroxides and azo compounds, or by irradiation of UV rays,visible light, α-ray, β-ray, γ-ray, electron ray or the like orcombination thereof.

The typical radical initiators which can be used, include peroxides suchas benzoyl peroxide, dicumyl peroxide, lauroyl peroxide,di-t-butylperoxy azelate, t-butyl-peroxy-2-ethyl hexanoate,t-butylperoxy laurate, t-butylperoxy benzoate,t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy acetate,bis(4-t-butyl-cyclohexyl)peroxy dicarbonate and t-butylperoxy isopropylcarbonate, and azo compounds such as azobisisobutyronitrile, which maybe used solely or in combination of two or more.

For initiation of polymerization by irradiation of UV-rays or the like,the known photo-initiators may be also used. The typicalphoto-initiators include benzophenone, 4,4-diethylaminobenzophenone,1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone,isoamyl p-dimethylaminobenzoate, methyl 4-dimethylaminobenzoate,benzoin, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropylether, 2,2-diethoxyacetophenone, methyl o-benzoylbenzoate,2-hydroxy-2-methyl-1-phenylpropan-1-one,2,4,6-trimethylbenzoyldiphenylphosphine oxide and bisacylphosphineoxide, which may be used solely or in combination of two or more, or incombination with any of the above radical initiators.

The typical polymerization processes for preparing the optical resins(e.g., a plastic lens) of this invention include casting polymerization.Specifically, the optical resin composition of this invention containinga radical or photo-initiator or both, which may be referred to as amonomer mixture, is poured between molds held by a gasket, tapes or thelike, during which some treatments such as defoaming may be conducted.

Then, it is subject to irradiation of UV rays or the like, or to heatingin an oven, or in combination thereof, and then a polymerization productmay be released.

A polymerization method or polymerization conditions for preparing theoptical resin of this invention cannot be generalized since they dependon the amounts and types of reagents such as initiators as well as typesand proportions of monomers.

For example, for irradiation of UV rays or the like, treatments such ascooling may be applied to prevent a monomer mixture from beingoverheated, or a wavelength cut filter or the like capable of cuttingrays below a particular wavelength may be used for irradiation with onlyrays within a wavelength band necessary for the desired polymerization.For heating in an oven, temperature may be controlled to select anoptimal thermal condition. In general, the temperature may be slowlyraised from a lower one to a predetermined one which is maintained tocomplete the polymerization. The polymerization period cannot begeneralized since it depends on the amounts and types of reagents suchas initiators as well as types and proportions of monomers.

Generally, it is possible to shorten the polymerization period by UVirradiation or the like.

For molding the resin of this invention, a variety of substances such aschain extenders, crosslinking agents, photostabilizers, U absorbers,,antioxidants, anti-coloring agents, dyes, perfumes and fillers, may beadded, depending on a purpose, as in the known molding methods.

The molded resin which has been released may be, if necessary, subjectedto any post-treatment such as annealing.

An optical resin obtained from the sulfur-containing O-(meth)acrylate ofthis invention has characteristics, that is, it has a high refractiveindex and is low-dispersing, and is excellent in thermal resistance,weather resistance and, in particular, impact resistance, and that itgenerates less unpleasant odor during processing. Furthermore, the resinof this invention can be formed as a molded resin which may be invarious forms by altering a mold in the casting polymerization, and canbe, therefore, used as an optical device such as lenses for eyeglassesand cameras, as well as a transparent resin for a variety ofapplications. In particular, it is suitable for an optical device suchas lenses for eyeglasses and cameras.

Furthermore, a lens prepared with the optical resin of this inventionmay be, if necessary, subjected to physical or chemical treatments suchas surface abrasion, antistatic treatment, hard coating, anti-reflectioncoating and dyeing, for improvements such as prevention of reflection;improvement in hardness, abrasion resistance or chemical resistance; andimpartation of antifogging or ornamental characteristics.

This invention will be specifically described by the following examples.The properties relevant to performance of an optical resin obtained,that is, a refractive index (n_(D)), Abbe number (ν), a specificgravity, impact resistance, odor during abrasion and appearance areevaluated as follows.

(1) A refractive index (n_(d)) and Abbe number (ν_(d)) were measured at20° C. using a Pulfrich refractometer.

(2) Appearance was visually observed.

(3) Impact resistance was evaluated by dropping a steel ball withdifferent weights on the center of a lens obtained from the height of127 cm. The result was represented by the weight of the heaviest steelball which did not crack or break the lens.

(4) Odor during abrasion was rated according to the following criteriaby detecting whether unpleasant sulfur odor was generated during cuttingand abrasion of an edge of a lens with an edger. The evaluation is asfollows:

◯; No unpleasant sulfur odor

Δ; Slight sulfur odor

×; Unpleasant sulfur odor

EXAMPLE 1

The organic layer was dried over anhydrous magnesium sulfate and toluenewas evaporated under a reduced pressure, to give 97.7 g (0.58 mol) of2-mercaptoethyl-3-chloropropionate represented by the following formula,as a colorless liquid.

The results of an elemental analysis for the product are shown below.

Composition: C₅H₉ClO₂S C H S Cl Observed (%) 35.4 5.3 19.3 21.1Calculated (%) 35.6 5.4 19.0 21.0

Its ¹H-NMR chart is shown in FIG. 1 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 2

To a reaction flask equipped with a stirring rod, a thermometer and aDean-Stark trap with a condenser were placed 21.2 g (0.20 mol) ofbenzaldehyde, 70.8 g (0.42 mol) of 2-mercaptoethyl 3-chloropropionate,0.3 g of p-toluene-sulfonic acid and 300 ml of toluene, and the mixturewas then heated for 2 hours under a controlled pressure between 80 and110 mmHg to maintain reflux at 50° C. to complete dithioacetalization.After cooling, the organic layer was then washed with water (once), 5%aqueous sodium bicarbonate solution (once) and then water (severaltimes).

The organic layer was dried over anhydrous magnesium sulfate and toluenewas evaporated under a reduced pressure, to give 82.1 g (0.19 mol) of acolorless liquid.

The liquid was dissolved in 200 ml of acetone, and the solution wasplaced into a reaction flask equipped with a stirring rod, a thermometerand a dropping funnel. The mixture was cooled to below 10° C., and withstirring, 43.0 g (0.42 mol) of triethylamine was slowly added, afterwhich the mixture was stirred for 10 hours at 25° C.

To the mixture were then added 200 ml of toluene and 200 ml of water toextract the reaction product into the organic layer and then the twophases were separated. The organic layer was washed with dilutedhydrochloric acid, diluted aqueous sodium bicarbonate solution and thenwater. The organic layer was dried over anhydrous magnesium sulfate andtoluene was evaporated under a reduced pressure, to give 66.9 g of thedesired sulfur-containing O-acrylate compound represented by thefollowing formula, i.e., bis(2-acryloyloxyethyl)dithioacetal benzene(0.190 mol) as a colorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₁₇H₂₀O₄S₂ C H S Observed (%) 57.8 5.8 18.4 Calculated (%)57.9 5.7 18.2

Its ¹H-NMR chart is shown in FIG. 2 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 3

Dithioacetalization and acrylation reactions were conducted as describedin Example 2, except that 21.2 g (0.20 mol) of benzaldehyde was replacedwith 30.4g (0.20 mol) of 4-methylthiobenzaldehyde, to give 76.4 g of thesulfur-containing O-acrylate compound represented by the followingformula, i.e., 4-methylthiobis(2-acryloyloxyethyl)dithio-acetal benzene(0.192 mol) as a colorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₁₈H₂₂O₄S₃ C H S Observed (%) 53.9 5.8 24.4 Calculated (%)54.2 5.6 24.1

Its ¹H-NMR chart is shown in FIG. 3 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 4

Dithioacetalization and acrylation reactions were conducted as describedin Example 2, except that 21.2 g (0.20 mol) of benzaldehyde was replacedwith 31.2 g (0.20 mol) of 1-naphthoaldehyde, to give 78.3 g of thesulfur-containing O-acrylate compound represented by the followingformula, i.e., 1-bis(2-acryloyloxyethyl)dithioacetal naphthalene (0.195mol) as a colorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₂₁H₂₂O₄S₂ C H S Observed (%) 62.6 5.6 16.1 Calculated (%)62.7 5.5 15.9

Its ¹H-NMR chart is shown in FIG. 4 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 5

Dithioacetalization and acrylation reactions were conducted as describedin Example 2, except that 21.2 g (0.20 mol) of benzaldehyde was replacedwith 22.4 g (0.20 mol) of 2-thiophenealdehyde, to give 54.1 g of thesulfur-containing O-acrylate compound represented by the followingformula, i.e., 2-bis(2-acryloyloxyethyl)dithioacetal thiophene (0.151mol) as a colorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₁₅H₁₈O₄S₃ C H S Observed (%) 50.4 5.0 26.7 Calculated (%)50.3 5.1 26.8

Its ¹H-NMR chart is shown in FIG. 5 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 6

Dithioacetalization and acrylation reactions were conducted as describedin Example 2, except that 21.2 g (0.20 mol) of benzaldehyde was replacedwith 24.0 g (0.20 mol) of phenylacetoaldehyde, to give 65.2 g of thesulfur-containing O-acrylate compound represented by the followingformula, i.e., phenylmethylenebis(2-acryloyloxyethyl)dithioacetal (0.178mol) as a colorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₁₈H₂₂O₄S₂ C H S Observed (%) 59.3 6.0 17.7 Calculated (%)59.0 6.1 17.5

Its ¹H-NMR chart is shown in FIG. 6 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 7

To a reaction flask equipped with a stirring rod, a thermometer and adropping funnel were placed 39.3 g (0.20 mol) ofmethylenebis(thioglycolic acid), 81.0 g (0.48 mol) of2-mercaptoethyl-3-chloropropionate, 0.1 g of dimethylaminopyridine and400 ml of chloroform. With stirring, to the mixture was slowly added asolution of 90.8 g (0.44 mol) of dicyclohexylcarbodiimide in 100 ml ofchloroform on a water bath, after which the mixture was stirred at 25°C. for additional 15 hours. Excessive dicyclohexylcarbodiimide wasquenched with acetic acid, and then urea formed was removed by vacuumfiltration. After evaporation of chloroform under a reduced pressure,the residual material was dissolved in 300 ml of toluene. The organiclayer was washed with 5% aqueous sodium bicarbonate solution and thenwater and dried over anhydrous magnesium sulfate. Toluene was evaporatedunder a reduced pressure to give 88.6 g (0.18 mol) of colorless liquid.

The liquid was dissolved in 300 ml of acetone and placed in a reactionflask equipped with a stirring rod, a thermometer and a dropping funnel.Cooling to below 10° C., to the mixture was slowly added 37.8 g (0.37mol) of triethylamine, after which the mixture was stirred at 25° C. foradditional 10 hours.

Then, to the mixture were 400 ml of toluene and 300 ml of water, and thereaction product was extracted into the organic layer. After separationof the two phases, the organic layer was washed with dilutedhydrochloric acid, diluted aqueous sodium bicarbonate solution andwater. The organic layer was dried over anhydrous magnesium sulfate, andtoluene was evaporated under a reduced pressure, to give 59.2 g of thedesired sulfur-containing O-acrylate compound, i.e.,methylenebis(acryloyloxyethylthio thioglycolate) (0.14 mol) as acolorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₁₅H₂₀O₆S₄ C H S Observed (%) 42.3 5.0 29.7 Calculated (%)42.4 4.8 30.2

Its ¹H-NMR chart is shown in FIG. 7 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 8

Dehydroesterification and acrylation reactions were conducted asdescribed in Example 7, except that 39.3 g (0.20 mol) ofmethylenebis(thioglycolic acid) of Example 7 was replaced with 30.0g(0.20 mol) of thiodiglycolic acid, to give 52.7 g of thesulfur-containing O-acrylate compound represented by the followingformula, i.e., bis(acryloyloxyethylthio)-thiodiglycolate (0.14 mol) as acolorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₁₄H₁₈O₆S₃ C H S Observed (%) 44.5 4.7 25.7 Calculated (%)44.4 4.8 25.4

Its ¹H-NMR chart is shown in FIG. 8 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 9

Dehydroesterification and acrylation reactions were conducted asdescribed in Example 7, except that 39.3 g (0.20 mol) ofmethylenebis(thioglycolic acid) of Example 7 was replaced with 57.3 g(0.20 mol) of methinetris(thioglycolic acid), and the amounts of thematerials used, i.e., 2-mercaptoethyl-3-chloropropionate,dicyclohexylcarbo-diimide and triethylamine were changed to 0.72 mol,0.66 mol and 0.59 mol, respectively, to give 100.6 g of thesulfur-containing O-acrylate compound represented by the followingformula, i.e., methinetris(acryloyloxyethylthio thioglycolate) (0.16mol) as a colorless and transparent material.

The results of an elemental analysis for the product are shown below.

Composition: C₂₂H₂₈O₉S₆ C H S Observed (%) 42.3 4.4 30.3 Calculated (%)42.0 4.5 30.6

Its ¹H-NMR chart is shown in FIG. 9 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLE 10

To a reaction flask equipped with a stirring rod, a thermometer and adropping funnel were placed 19.0 g (0.10 mol) ofbis(isocyanatomethylthio)methane, 15 mg of dimethyltin dichloride and100 ml of toluene. With stirring, to the mixture was slowly added 33.7 g(0.20 mol) of 2-mercaptoethyl-3-chloropropionate on a water bath, afterwhich the mixture was stirred for 2 hours at the same temperature andthen for 2 hours at 50° C. After cooling, crystals generated werefiltered, washed and dried, to give 42.5 g (0.08 mol) of white crystals.

The crystals were dissolved in 200 ml of acetone and placed in areaction flask equipped with a stirring rod, a thermometer and adripping funnel. To the solution was slowly added 17.1 g (0.17 mol) oftriethylamine, after which the mixture was stirred at 25° C. foradditional 10 hours.

Then, to the mixture were 200 ml of toluene and 200 ml of water, and thereaction product was extracted into the organic layer. After separationof the two phases, the organic layer was washed with dilutedhydrochloric acid, diluted aqueous sodium bicarbonate solution andwater. The organic layer was dried over anhydrous magnesium sulfate, andtoluene was evaporated under a reduced pressure, to give 29.7 g of thedesired sulfur-containing O-acrylate compound (0.065 mol) as whitecrystals.

The results of an elemental analysis for the product are shown below.

Composition: C₁₅H₂₂N₂O₆S₄ C H S Observed (%) 39.8 5.1 28.5 Calculated(%) 39.6 4.9 28.3

Its ¹H-NMR chart is shown in FIG. 10 (solvent: CDCl₃, reference:tetramethylsilane).

EXAMPLES 11 TO 19

To 50 g of each product of Examples 2 to 10 was added 50 to 100 mg of2-hydroxy-2-methyl-1-phenylpropan-1-one as a photoinitiator, and themixture was thoroughly mixed. After fully defoaming, the mixture waspoured into a mold consisting of glass templates and a gasket. The moldwas irradiated with UV rays for 10 to 60 sec., and was then heated at120° C. for 1 hour, to polymerize the composition. After polymerization,it was slowly cooled and the molding product was removed from the mold.The physical properties of the molding products, i.e., lenses, are shownin Table 1.

TABLE 1 Refractive Abbe Mononer Appearance Index Number Example 11Compd. of Ex. 2  CL/TR* 1.600 36.5 Example 12 Compd. of Ex. 3 CL/TR1.624 30.4 Example 13 Compd. of Ex. 4 CL/TR 1.637 27.5 Example 14 Compd.of Ex. 5 CL/TR 1.609 35.8 Example 15 Compd. of Ex. 6 CL/TR 1.600 34.6Example 16 Compd. of Ex. 7 CL/TR 1.602 38.5 Example 17 Compd. of Ex. 8CL/TR 1.589 40.7 Example 18 Compd. of Ex. 9 CL/TR 1.606 38.2 Example 19 Compd. of Ex. 10 CL/TR 1.632 37.5 *CL/TR: colorless and transparent

EXAMPLE 20

To 35 g of bis(2-acryloyloxyethyl)dithioacetal benzene obtained inExample 2 were added 15 g of bis(4-acryloxydiethoxyphenyl)methane and 50mg of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photoinitiator, andthe mixture was thoroughly mixed. After fully defoaming, the compositionwas poured into a mold consisting of glass templates and tapes.

The mold was irradiated with UV rays for 10 sec., and was then heated at120° C. for 1 hour, to polymerize the composition. After polymerization,it was slowly cooled and the molding product was removed from the molds.The physical properties of the molding products, i.e., lenses, are shownin Table 2.

EXAMPLES 21 TO 26

The procedure as described in Example 20 was conducted, except that themonomer compositions listed in Table 2 were used, to give plasticlenses, whose evaluation results are shown in Table 2 together withthose of Example 20.

The results in Table 2 indicate that the plastic lenses of Examples 20to 26 were colorless and transparent; had a good balance among arefractive index (n_(d)), Abbe number (ν_(d)) and a specific gravity;were excellent in impact resistance; and generated no unpleasant odorduring abrasion of the resins.

Comparative Examples 1 to 3

The procedure as described in Example 20 was conducted, except that themonomer compositions listed in Table 2 were used, to give plasticlenses, whose evaluation results are shown in Table 2 together withthose of Examples 20 to 26.

The results in Table 2 indicate that the plastic lenses of ComparativeExamples had lower impact resistance than those of Examples 20 to 26,and generated sulfur odor during abrasion of the resins.

TABLE 2 Proportions of monomers Spec. Impact Appear- (% by weight) n_(d)ν_(d) Grav. Resist. Odor ance Example Compd. of 70 1.590 36 1.27 117 g ◯CL/TR* 20 Ex. 2 BSFA 30 Example Compd. of 65 1.591 36 1.27  67 g ◯ CL/TR21 Ex. 2 BSFA 30 Divinyl- 5 benzene Example Compd. of 65 1.598 33 1.28 67 g ◯ CL/TR 22 Ex. 3 BSFA 30 TEGDMA 5 Example Compd. of 50 1.590 321.25 117 g ◯ CL/TR 23 Ex. 4 BSFA 50 Example Compd. of 70 1.590 35 1.26 67 g ◯ CL/TR 24 Ex. 6 BSFA 30 Example Compd. of 80 1.595 38 1.36 117 g◯ CL/TR 25 Ex. 7 BSFA 20 Example Compd. of 80 1.591 38 1.37 117 g ◯CL/TR 26 Ex. 10 BSFA 15 TEGDMA 5 Comp. DTAET 80 1.609 42 1.29  16 g xCL/TR Ex. 1 DCPA 20 break Comp. AETE 70 1.581 40 1.25  16 g Δ CL/TR Ex.2 Styrene 30 break Comp. XDMET 80 1.588 39 1.31  16 g Δ CL/TR Ex. 3 BSAM20 break *CL/TR: colorless and transparent BSFA:bis(4-acryloxydiethoxyphenyl)methane TEGDMA: tetraethylene glycoldimethacrylate DTAET: 2,5-bis(acryloxyethylthiomethyl)-1,4-dithianeAETE: bis(acryloxyethylthio)ethane XDMET:p-bis(β-methacryloxyethylthio)xylylene BSAM:2,2-bis(4-methacryloxydiethoxyphenyl)propane DCPA: dimethyloltricyclodecane diacrylate

What is claimed is:
 1. A thiol compound represented by the followingformula (2):

wherein X represents Cl or Br; R represents hydrogen atom or methylgroup; and l represents an integer from 1 to
 3. 2. The thiol compoundaccording to claim 1, wherein the thiol compound is a compoundrepresented by the following formula: